Device for polishing outer peripheral edge of semiconductor wafer

ABSTRACT

A polishing machine for a peripheral edge of a semiconductor wafer comprises a rotary mechanism  2  which rotates a stack  1  of semiconductor wafers  4  mounted thereon, and a polishing mechanism  3  which is arranged to be movable in the radial direction of the rotary mechanism  2  and polishes the peripheral edges of the rotating semiconductor wafers  4  by means of contactless polishing. Minute gaps s are formed between the rotary column  10  of the polishing mechanism  3  and the stack  1  of semiconductor wafers  4 , and polishing solution is drawn into these minute gaps s. The peripheral edges of the semiconductor wafers  4  are polished by means of contactless polishing, using polishing abrasive particles included in polishing solution.

BACKGROUND OF THE INVENTION

The present invention relates to a polishing machine for polishing theperipheral edge of a semiconductor wafer.

The peripheral edges of semiconductor wafers made from silicon and thelike are chamfered, but in recent years, further polishing of theperipheral edge has come to be conducted in order to prevent particleformation on the peripheral edge, imperfections arising during handling,and the like. Edge processing methods are known, for example, a methodfor rotating a semiconductor wafer, and pressing a similarly rotatingpolishing pad thereto, while supplying polishing solution, as describedin Japanese Patent Laid-Open Publication No. Hei. 11-104942, and amethod for pressing a rotating polishing pad to a plurality of stackedsemiconductor wafers, while supplying polishing solution thereto, asdescribed in Japanese Patent Laid-Open Publication No. Hei. 05-182939.

Chamfering processes of the peripheral edge of semiconductor wafers havehad the following problems, due to the fact that the chamfering radiusis small and the chamfering corners are steeply inclined: even with aflexible polishing pad it is unfeasible to obtain uniform contact withthe surface of the peripheral edge, making it difficult to obtain highlyprecise polishing, and because only a small part of the surface of thepad is in contact with the edge surface, for instance a point or a line,the polishing process is inefficient. Additionally, constant adjustmentswere required in order to maintain favorable polishing conditions,including changing the polishing pad at appropriate intervals.

SUMMARY OF THE INVENTION

In light of the above, it is an object of the present invention toprovide a polishing machine for a peripheral edge of a semiconductorwafer, capable of highly precise, uniform, highly efficient, and stablepolishing.

In order to achieve the above-mentioned object, the present inventionprovides a construction comprising: a rotary mechanism for holding asemiconductor wafer while rotating it in a prescribed direction; arotary body which rotates relative to the semiconductor wafer whilemaintaining a prescribed gap from a periphery thereof, having a rotaryaxis which is set in the same direction as the rotary axis of thesemiconductor wafer; a polishing solution channel for channeling theflow of polishing solution to said gap; and a polishing solution supplyportion for supplying polishing solution to the polishing solutionchannel.

Additionally, in order to achieve the above-mentioned object, thepresent invention provides a construction comprising: a rotary mechanismfor holding a semiconductor wafer while rotating it in a prescribeddirection; a rotary body which rotates relative to the semiconductorwafer while maintaining a prescribed gap from a periphery thereof,having a rotary axis which is set in the same direction as the rotaryaxis of the semiconductor wafer; a polishing solution tank for immersingthe rotary mechanism and rotary body in polishing solution; and apolishing solution circulation portion for circulating the polishingsolution in and out of the polishing solution tank.

Since according to the present invention, contactless polishing isconducted by drawing polishing solution into the gap between theperipheral edge of semiconductor wafer and the rotary body, theperipheral edge of semiconductor wafer can be polished in a highlyprecise and uniform manner. Additionally, because the polishing pad ofexisting methods is not needed, polishing pad changing and adjustmentsare not necessary, allowing for a stable polishing process.

In the above-mentioned construction, the rotary mechanism holds onesemiconductor wafer, or a plurality thereof in a stacked state. In thefirst case, the single semiconductor wafer held in the rotary mechanismis polished (the so-called single-wafer method), and in the second case,the plurality of semiconductor wafers held in the rotary mechanism arepolished in turn (the so-called batch method).

Additionally, in the above-mentioned construction, a dynamic pressuregenerating grooves can be formed on the peripheral surface of the rotarybody, facing the periphery of the semiconductor wafer. Because,according to this construction, the flow speed of polishing solution isincreased through the dynamic pressure effect of the dynamic pressuregenerating grooves, the polishing efficiency is increased.

Additionally, in the above-mentioned construction, a magnet may beinstalled in the rotary body, and a magnetic polishing solution may beused as the polishing solution. Because, according to this construction,the magnetic polishing solution is confined by the magnet of the rotarybody, the polishing efficiency is increased.

Additionally, in the above-mentioned construction, at least theperipheral surface of the rotary body facing the periphery of thesemiconductor wafer may be formed of an elastic material with a hardnessin the range of 7-40 Hs. The entire rotary body may be formed of anelastic material having a hardness of 7-40 Hs, and only the outersurface layer of the rotary body, including the peripheral surface, maybe formed of an elastic material having a hardness of 7-40 Hs. Theelastic material having a hardness of 7-40 Hs may be, for example, arubber such as chloroprene rubber, or alternatively a synthetic resinformed into a porous (spongy) state by such means as expansion molding.The term “Hs” used here refers to hardness as measured by a JIS-standardType A spring hardness tester (used to measure the hardness of rubber).This is widely used to express the hardness of a material in order toevaluate the elasticity of such elastic materials as rubber.

In the polishing machine of the present invention, the polishingefficiency and coarseness of the polished surface are influenced by suchfactors as polishing speed (the relative rotating speed of thesemiconductor wafer and the rotary body), the flow speed and pressure ofpolishing solution in the above-mentioned gaps, the viscosity of thepolishing solution, and the concentration and diameter of abrasiveparticles in the polishing solution. However, by forming at least theperipheral surface of the rotary body from an elastic material with ahardness of 7-40 Hs, variations in the values of the above-mentionedfactors are absorbed by the appropriate elasticity of the rotary bodyperipheral surface, making it possible to constantly obtain a stablepolishing efficiency and level of polished surface coarseness.Additionally, during the polishing process, the polishing speed may bechanged (for example, polishing with a relatively high polishing speedfor a prescribed length of time from the start of the polishing process,then polishing at a relatively lower polishing speed for the remainderof the polishing process) without changing the semiconductor waferholding status, the polishing solution, or the like, enabling highlyprecise, highly efficient polishing.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of a polishing machine for a peripheraledge of a semiconductor wafer according to a first embodiment of thepresent invention.

FIG. 2 shows the polishing surface of the polishing mechanism accordingto the first embodiment of the present invention.

FIG. 3 shows the operational states of the polishing mechanism accordingto the first embodiment of the present invention.

FIG. 4 shows an example of the polishing machine according to the firstembodiment of the present invention, using differently shaped spacers.

FIG. 5 is a perspective view of a polishing machine for a peripheraledge of a semiconductor wafer according to a second embodiment of thepresent invention.

FIG. 6 is a perspective view of a polishing machine for a peripheraledge of a semiconductor wafer according to a third embodiment of thepresent invention.

FIG. 7 shows a magnetic polishing mechanism of a polishing machine for aperipheral edge of a semiconductor wafer according to a fourthembodiment of the present invention.

FIG. 8 is a perspective view of a polishing machine for a peripheraledge of a semiconductor wafer according to a fifth embodiment of thepresent invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

The preferred embodiments of the current invention will be described indetail below, making reference to the drawings.

As shown in FIG. 1, the polishing machine for a peripheral edge of asemiconductor wafer according to the first embodiment of the presentinvention comprises a rotary mechanism 2 on which is mounted and rotateda stack 1 of semiconductor wafers 4, and a polishing mechanism 3 whichcan be moved as desired along the radial direction of the rotarymechanism 2, and which polishes the peripheral edges of the rotatingsemiconductor wafers 4 via a contactless polishing process.

The peripheral edges of semiconductor wafers 4, having for example theshapes of circular plates, are chamfered as necessary, and notches(omitted from the drawing) are formed on the periphery at prescribedlocations. The stack 1 of the semiconductor wafers 4 is aligned with thenotches, and formed by placing spacers 5 between each semiconductorwafer 4. Note that the stack 1 of semiconductor wafers 4 is preferablyprovided with spacers 5 on the top and the bottom thereof, in order tokeep from marking the surface of the wafers 4 when the stack 1 is lockedinto the rotary mechanism 2.

Rotary mechanism 2 comprises a turntable 6 on which is mounted the stack1 of semiconductor wafers 4, and a locking piece 7 for pressing thestack 1 of semiconductor wafers 4 onto the turntable 6.

Polishing mechanism 3 has as the chief elements of its construction ahousing 11, and a rotary body freely rotating and accommodated in thehousing 11, for example a rotary column 10. This polishing mechanism 3is mounted on a slide rail 8 installed in the radial direction of therotary mechanism 2, and can move freely along the slide. Additionally,the elasticity means not shown in the drawing constantly presses thepolishing mechanism 3 against the rotary mechanism 2 in the direction ofthe rotary mechanism 2 center through a prescribed level of elasticpressure.

As shown in FIG. 2, the housing 11 is provided with a contact surface13, for example an approximately rectangular parallelepiped member onthe side facing the rotary mechanism 2. The contact surface 13 contactsthe periphery of the stack 1 along the contour of the outer surfacethereof. The contact surface 13 has a curved inner side shape in orderto conform to the outer shape of the stack 1 of semiconductor wafers 4.An aperture 12 is formed on the contact surface 13 in order to exposethe rotary column 10 inside the housing 11. The periphery of theaperture 12 is sealed in order to keep the polishing solution fromleaking.

The rotary column 10, for example a cylindrical member formed from metalor other materials having necessary rigidity, is accommodated within thehousing 11 so that it can rotate freely, rotating on the vertical axisunder the power of freely chosen rotary drive means. The outer surface10 a of the rotary column 10 is exposed at the aperture 12, and thepolishing solution flow channel 9 narrows at the aperture 12. As shownin FIG. 3, the rotary column 10 faces the stack 1 at the aperture 12 viaa minute gap s, and rotates in the opposite direction relative thereto.

As shown in FIG. 3, the housing 11 is equipped with the polishingsolution flow channel 9 which channels polishing solution via the gap sof the aperture 12. The polishing solution flow channel 9 runs throughthe gap s of the aperture 12 at either side, and has a supply channel 14and a drain channel 15 shown on the right and left sides of the drawing.

The polishing solution, for example an aqueous solution includingpolishing abrasive particles, is pressure-fed down the supply channel 14using prescribed levels of pressure and heat, by means of an externalpump and heat exchanger (omitted from the drawing). The polishingsolution then flows from the supply channel 14 to the drain channel 15by way of the gap s, forming in its totality the polishing solution flowchannel 9.

A spring mounted on the slide rail 8 (omitted from the drawing) pressesthe polishing mechanism 3 against the stack 1 of semiconductor wafers 4.This absorbs differences in the diameters of the stack 1 and rotarycolumn 10 and rotary vibration when the polishing machine for aperipheral edge is operated, ensuring contact between the contactsurface 13 and stack 1, maintaining the appropriate size of theabove-mentioned minute gap s, and preventing the leakage of polishingsolution from the contact surface 13.

Then, because the polishing solution flow channel 9 narrows at theminute gap s, the flow speed and pressure of polishing solution passingtherethrough increases, and the polishing abrasive particles collidewith the peripheral edges of the semiconductor wafers 4 at a nearly flatangle. This enables the polishing mechanism 3 to polish the peripheraledges of the semiconductor wafers 4 with a high level of precision bydestroying minute quantities thereof. Additionally, since this polishingmachine polishes by causing polishing abrasive particles to collide withthe edges during the flow of polishing solution, it is possible touniformly polish the peripheral edges.

The above has described the first embodiment of the polishing machinefor a peripheral edge, but this embodiment may be modified in a numberof ways.

For example, as shown in FIG. 4, the diameter of the spacer 5 may beslightly made larger than that of the semiconductor wafer 4, to form aprescribed minute gap s between the peripheral edges of thesemiconductor wafers 4 and the rotary column 10 by causing the spacers 5to contact the rotary column 10. Additionally, grooves 16 may be formedaround the circumference of the spacers 5 in conformity with the edgesof the chamfered portions of the semiconductor wafers 4, in order touniformly draw polishing solution in around the entire edges of thesemiconductor wafers 4. Additionally, in the above mentioned embodiment,the rotary axis of the rotary mechanism 2 which rotates the stack ofsemiconductor wafers 4 is set up along the vertical axis. However, therotary axis of the rotary mechanism (the rotary axis of thesemiconductor wafers 4) may be set up along the horizontal axis, and therelated apparatuses may be arranged to correspond thereto.

Additionally, the polishing mechanism 3 does not only move along theradial direction of the stack 1 of semiconductor wafers 4, but is alsoprovided with a mechanism which can move along the periphery of thestack 1 of semiconductor wafers 4. Moreover, the polishing solution mayinclude surfactants and viscosity modifiers, and it is also permissibleto modify the diameter of the polishing abrasive particles in a stepwiseor continuous manner, in accordance with the process in question toperform sequentially coarse processing to finishing without removing awork. In addition, it is possible to use a polishing solution havingmechanochemical polishing effects which includes chemically active solidparticles or chemical solutions, or to use a polishing solution whosepolishing abrasive particles themselves have mechanochemical polishingeffects. It is also possible to form grooves on the surface of therotary column 10, parallel to the rotary axis or in a spiralconfiguration, as dynamic pressure generating grooves in order toincrease the flow speed of polishing solution at the gap between therotary column 10 and semiconductor wafers 4, to form a textured surface,to form a hydrophilic membrane on the surface of the rotary column 10,or to construct the rotary column 10 from a porous material.Alternatively, it is possible to take a replica of the peripheral edgeof a wafer using a softened polymer material, and use this as the rotarycolumn 10.

Next, a polishing machine for a peripheral edge of a semiconductor waferaccording to the second embodiment of the present invention will bedescribed.

As shown in FIG. 5, the polishing machine for a peripheral edge of asemiconductor wafer according to this embodiment is made up of theentire polishing machine for a peripheral edge of the first embodiment,immersed in a polishing solution tank 21 filled with polishing solution.

The polishing solution tank 21 is equipped with a polishing solutioncirculation apparatus 25. The polishing solution circulation apparatus25 has two communicating pipes: a supply pipe 22 installed in the upperportion of the polishing solution tank 21, and a drain pipe 23 installedin the lower portion thereof, and circulates polishing solution in andout of the polishing solution tank 21. The polishing solution iscollected from the lower portion of the polishing solution tank 21 bythe polishing solution circulation apparatus 25, and after itstemperature is regulated inside the heat exchanger 26, it is againsupplied to the upper portion of the polishing solution tank 21.

The semiconductor wafers 4 are stacked, sandwiched by spacers 5 in thesame manner as the first embodiment. In the approximate center of thepolishing solution tank 21 is installed a rotary mechanism 2, whichrotates the stack 1 of semiconductor wafers 4 mounted thereon. As in thefirst embodiment, the rotary mechanism 2 is equipped with a turntable 6on which is mounted the stack 1 of semiconductor wafers 4, and a lockingpiece 7 which presses the stack 1 of semiconductor wafers 4 against theturntable 6, and fixes it in place. A slide rail 8 is installed in theradial direction of the rotary mechanism 2. The slide rail 8 axiallysupports a rotary column 10 which is freely movable. The rotary column10 is constructed so as to rotate with the stack 1 of semiconductorwafers 4, mediated by a minute gap s.

In this polishing machine for a peripheral edge, the rotary mechanism 2upon which is mounted the stack 1 of semiconductor wafers 4 and therotary column 10 rotate in the opposite direction relative to eachother, in a state in which polishing solution has penetratedtherebetween. The polishing solution is drawn into the space between therelatively rotating stack 1 of semiconductor wafers 4 and rotary column10 by means of viscosity. Fluid mechanics cause the speed of thepolishing solution to increase as it is drawn into the minute gap s, dueto the narrowing thereof. Then, when the polishing abrasive particles inthe polishing solution pass through the minute gap s, they collide withthe peripheral surfaces of the semiconductor wafers 4 at a nearly flatangle, polishing the peripheral edges thereof.

In other words, in the same manner as the polishing machine for aperipheral edge of the first embodiment, this polishing machine for aperipheral edge is able to polish the peripheral edges of thesemiconductor wafers 4 with a high level of precision by destroyingminute quantities thereof.

It is also permissible to form grooves on the surface of the rotarycolumn 10 of this polishing machine for a peripheral edge, parallel withthe rotary axis or in a spiral configuration, or process it to give it atextured surface. Additionally, it is possible to form a hydrophilicmembrane on the surface of the rotary column 10, or to construct therotary column 10 from a porous material. The shapes of the flow channelcover and/or polishing solution tank 21 may be changed in order tominimize the flow of polishing solution circulating therein.

Additionally, in the present embodiment the diameter of the spacer 5 maybe slightly made larger than that of the semiconductor wafer 4 to form aprescribed minute gap s between the peripheries of the semiconductorwafers 4 and the periphery of the rotary column 10 by causing thespacers 5 to contact the rotary column 10.

Next, a polishing machine for a peripheral edge of a semiconductor waferaccording to the third embodiment of the present invention will bedescribed.

As shown in FIG. 6, in this polishing machine for a peripheral edge, arotary mechanism 2 upon which is mounted a stack 1 of semiconductorwafers 4, and an interior pipe body 32 mounted on the periphery of thestack 1 of semiconductor wafers 4, are accommodated inside anapproximately cylindrical exterior pipe body 31 installed on the basethereof. Polishing solution is drawn into the minute gap between thestack 1 of semiconductor wafers 4 and interior pipe body 32, polishingthe peripheral edges of the semiconductor wafers 4.

As in the first embodiment, the rotary mechanism 2 is equipped with aturntable 6 upon which is mounted the stack 1 of semiconductor wafers 4,and a locking piece 7 which presses the stack 1 of semiconductor wafers4 onto the turntable 6, and fixes it thereto.

The exterior pipe body 31 serving as a polishing solution supply portionis affixed to the base so as to be on the same axis as the rotarymechanism 2. The exterior pipe body 31 is equipped with a storageportion 33 in order to create a space between it and the interior pipebody 32, and store polishing solution. In the interior of the exteriorpipe body 31, the upper end 33 a and lower end 33 b are sealed in orderto prevent leakage of the polishing solution from the storage portion33. The side of the exterior pipe body 31 is equipped with a supply pipe34 for supplying polishing solution, and a drain pipe 35 for drainingthe polishing solution. Polishing solution of a prescribed pressure issupplied to the storage portion 33 via the supply pipe 34 from apolishing solution supply apparatus (omitted from the drawing).

The interior pipe body 32, serving as a rotary column, is accommodatedbetween the exterior pipe body 31 and the stack 1 of semiconductorwafers 4, and rotated by a rotary mechanism not shown in the drawing.The inner surface 35 of the interior pipe body 32 faces the peripheralsurface of the stack 1 of semiconductor wafers 4 mediated by a minutegap. Vertically aligned dynamic pressure grooves 36 formed on the innersurface 35 of the interior pipe body 32 are distributed around theperiphery at prescribed intervals. The dynamic pressure grooves 36 areequipped ith a plurality of polishing solution supply apertures 37 whichare linked to the storage portion 33 of the exterior pipe body 31, inorder to supply polishing solution to the interior of the interior pipebody 32.

This polishing machine for a peripheral edge rotates the stack 1 ofsemiconductor wafers 4 by means of the rotary mechanism 2 and rotatesthe interior pipe body 32 in the opposite direction relative to thestack 1 of semiconductor wafers 4, while supplying polishing solution ata prescribed pressure to the exterior pipe body 31. At this time,dynamic pressure generated between the stack 1 of semiconductor wafers 4and interior pipe body 32 draws polishing solution between the innersurface 35 of the interior pipe body 32 and the stack 1 of semiconductorwafers 4 from the dynamic pressure grooves 36 of the interior pipe body32.

The flow speed and pressure of the polishing solution drawn between theinner surface 35 of the interior pipe body 32 and the stack 1 ofsemiconductor wafers 4 is accelerated due to the narrowing of the flowchannel therebetween. Additionally, due to the fact that the polishingsolution flows around the peripheries of the semiconductor wafers 4, thepolishing abrasive particles in the polishing solution pass collide withthe peripheral surfaces of the semiconductor wafers 4 at a nearly flatangle, polishing the peripheral edges thereof. In other words, in thesame manner as the polishing machine for a peripheral edge of the firstembodiment, this polishing machine for a peripheral edge is able topolish the peripheral edges of the semiconductor wafers 4 with a highlevel of precision by destroying minute quantities thereof.

The dynamic pressure grooves 36 formed on the interior pipe body 32 maybe wedge-shaped, in order to obtain a greater fluid-mechanical effect.Additionally, it is permissible to form a hydrophilic membrane on thesurface of the interior pipe body 32, process it to give it a texturedsurface, or construct the interior pipe body 32 from a porous material.Moreover, as in the second embodiment, a construction in which theentire apparatus is immersed in polishing solution may be employed.Moreover, the rotary axis of the stack 1 of semiconductor wafers 4 maybe given a horizontal construction and the related apparatuses may bearranged to correspond thereto. It is also permissible to employ aconstruction which locks the exterior pipe body 31 and interior pipebody 32 in place, and rotates the stack 1 of semiconductor wafers 4, andin this case, it is also permissible if the interior and exterior pipesdo not completely enclose the wafers, or if they are notched.

It is also possible for the components adjacent to the semiconductorwafers 4 of the polishing machine for a peripheral edge of theabove-mentioned embodiments 1-3 to be formed from high-purity silicon orhigh-purity quartz. Additionally, the rotary column 10 and/or interiorpipe body 32 may be made of, for example, polyurethane.

With the above-mentioned construction, the components of thepolyurethane rotary column 10 or interior pipe body 32 that are adjacentto the stack 1 of semiconductor wafers 4 are deformed in conformity withthe peripheral shape of the stack 1, and form a minute gap s togetherwith the semiconductor wafers 4 within the polishing solution. Then,polishing solution is drawn between it and the stack 1 of semiconductorwafers 4, generating a high-speed fluid bearing-type flow. At this time,the polishing abrasive particles included in the fluid collide with thesurface of the semiconductor wafers 4, achieving high-precisionpolishing by destroying minute quantities thereof.

For example, in an embodiment in which the rotary column 10 is made ofpolyurethane, if the rotary column 10 is pressed against the peripheryof the stack 1 of semiconductor wafers 4, then it is easy to establish aminute gap s, since the shape thereof is freely changed to conform tothe shape of the periphery of the stack 1 of semiconductor wafers 4 anda minute gap is formed between it and the semiconductor wafers 4.

Alternatively, it is possible to form the rotary column 10 in itsentirety, or the surface portion including the peripheral surface 10 athereof, of a rubber such as chloroprene rubber, or alternatively asynthetic resin formed into a porous (spongy) state, using an elasticmaterial with a hardness of 7-40 Hs. Even if there are fluctuations inpolishing speed (the relative rotary speed of the semiconductor waferand rotary body), the flow speed and pressure of the polishing solutioninside the minute gap s, viscosity of the polishing solution, and theconcentration and diameters of the abrasive particles included in thepolishing solution, it is possible to constantly obtain a stablepolishing efficiency and polishing surface grain, since thesefluctuations are absorbed by the appropriate elasticity of theperipheral surface 10 a of the rotary column 10. Additionally, duringthe polishing process, the polishing speed may be changed (for example,polishing with a relatively high polishing speed for a prescribed lengthof time from the start of the polishing process, then polishing at arelatively lower polishing speed for the remainder of the polishingprocess) without changing the semiconductor wafer holding status, thepolishing solution, or the like, enabling highly precise, highlyefficient polishing.

Next, a polishing machine for a peripheral edge of a semiconductor waferaccording to a fourth embodiment of the present invention will bedescribed.

AS shown in FIG. 7, although the basic construction of the polishingmachine for a peripheral edge of this embodiment is the same as that ofthe polishing machine for a peripheral edge of the first embodiment,unlike the polishing machine for a peripheral edge of the firstembodiment, this embodiment is equipped with a magnetic polishingmechanism 41 having n-polar 44 and s-polar 45 magnets arrayed inalternation around the periphery of the outer surface of the rotarycolumn 42, and using magnetic polishing solution including polishingabrasive particles in the magnetic fluid.

Since magnets 44 and 45 are installed in the outer surface of the rotarycolumn 42, the magnetically charged magnetic polishing solution is drawnby the magnetic fields of the magnets 44 and 45 of the rotary column 42.Then, by rotating the stack 1 of semiconductor wafers 4 and the rotarycolumn 42 in opposite directions relative to each other, the magneticpolishing solution is drawn into the minute gap s of the polishingsolution flow channel 46 along the surface of the rotary column 42. Thisenables high-precision polishing of the peripheral edges of thesemiconductor wafers 4 by destroying minute quantities thereof, in thesame manner as the polishing machine for a peripheral edge of the firstembodiment.

This polishing mechanism 41 may be constructed in such a manner that itdoes not only move in the radial direction of the stack 1 ofsemiconductor wafers 4, but also moves in the peripheral direction alongthe circular periphery thereof. Moreover, the magnetic polishingsolution may contain surfactants and viscosity modifiers. In addition, apolishing solution having mechanochemical polishing effects whichincludes chemically active solid particles or chemical solutions, or apolishing solution whose polishing abrasive particles themselves havemechanochemical polishing effects may be used. It is also possible toform grooves on the surface of the rotary column 42, parallel to theaxis or in a spiral configuration, as dynamic pressure grooves in orderto increase the flow speed of magnetic polishing solution through theminute gap s by means of a fluid-mechanical effect. It is also possibleto form a hydrophilic membrane on the surface of the rotary column 42.

In the embodiment shown in FIG. 7, the outer diameter of the spacer 5 isslightly made larger than that of the semiconductor wafer 4 to contactthe rotary column 42 with the peripheries of the spacers 5, forming aminute gap between the rotary column 42 and semiconductor wafers 4.Additionally, grooves 47 are provided in the peripheral direction of thespacers 5, so that the magnetic polishing solution flows uniformly alongthe edges of the semiconductor wafers 4.

Note that in FIG. 7, although the rotary axis of the rotary mechanism isset up along the vertical axis, the rotary axis of the rotary mechanismmay be set along the horizontal axis, and the related apparatuses may bearranged to correspond thereto. Moreover, it is also possible to employa construction immersing the entire apparatus in magnetic polishingsolution, in the same manner as the second embodiment.

Next, a polishing machine for a peripheral edge of a semiconductor waferaccording to the fifth embodiment of the present invention will bedescribed.

As shown in FIG. 8, in the polishing machine for a peripheral edge ofthis embodiment, a rotary mechanism 2 upon which is mounted a stack 1 ofsemiconductor wafers 4 and an interior pipe body 52 surrounding thestack 1 of semiconductor wafers 4 are accommodated within a generallycylindrical exterior pipe body 51 installed on the base thereof. Note,however, that in the present embodiment, an interior pipe body 52 isused which has n-polar 54 and s-polar 55 magnets arrayed in alternationaround the periphery of the inner surface thereof, and a magneticpolishing solution is used including polishing abrasive particles inmagnetic fluid.

The exterior pipe body 51, in the same manner as the exterior pipe body31 according to the third embodiment, is equipped with an internalstorage portion 56, a supply pipe 57 that supplies magnetic polishingsolution at a prescribed pressure to a storage portion 56 from amagnetic polishing solution supply apparatus not shown in the drawing,and a drain pipe 58 that drains magnetic polishing solution from thestorage portion 56.

This polishing machine for a peripheral edge rotates a stack 1 ofsemiconductor wafers 4 by means of a rotary mechanism 2, and rotates aninterior pipe body 52 by means of the rotary mechanism 2 not shown inthe drawing in the direction opposite to that of the stack 1 ofsemiconductor wafers 4, while supplying the magnetic polishing solutionwith a predetermined pressure into the exterior pipe body 51.

Magnetic polishing solution is supplied to the gap between the interiorpipe body 52 and the stack 1 of semiconductor wafers 4 from a pluralityof supply apertures 59 in the interior pipe body 52. Then, the magneticpolishing solution is drawn by the magnets 54 and 55 installed in theinner surface of the interior pipe body 52, and drawn into the gapbetween the interior pipe body 52 and stack 1 of semiconductor wafers 4which are rotating opposite relative one another.

At this time, since the polishing abrasive particles in the magneticpolishing solution collide with the peripheral edges of thesemiconductor wafers 4 at a nearly flat angle, it is possible to conducthigh-precision polishing of the peripheral edges of the semiconductorwafers 4 by means of a minute-quantity destruction effect.

Note that in order to increase the speed of the magnetic polishingsolution flow at the gap between the interior pipe body 52 and thesemiconductor wafers 4 through a fluid-mechanical effect, it is possibleto form grooves on the inner surface of the interior pipe body 52parallel to the rotary axis thereof or in a spiral configuration, asdynamic pressure grooves, and it is also possible to make these grooveswedge-shaped in order to obtain a greater fluid-mechanical effect.

The above has described embodiments of the present invention, but thepresent invention is not limited to these embodiments. For example, inthe stack of semiconductor wafers, wafers are stacked sandwiched byspacers, but the form is not limited to a stack of semiconductor wafers.Additionally, the constructions of embodiments 1 to 6 may be combined asdesired. Furthermore, although in the embodiments described above aplurality of semiconductor wafers are simultaneously polished using theso-called batch method, it is also possible to use a construction inwhich the rotary mechanism holds and rotates a single semiconductorwafer, polishing a single semiconductor wafer at a time (the so-calledsingle-wafer method).

1. A polishing machine for a peripheral edge of a semiconductor wafer, said machine comprising: a rotary mechanism for holding a semiconductor wafer while rotating it in a prescribed direction; a rotary body which rotates relative to the semiconductor wafer while maintaining a prescribed gap from a periphery of said semiconductor wafer, having a rotary axis which is set in the same direction as the rotary axis of said semiconductor wafer, so that the rotary body and the semiconductor wafer are not in contact with each other during a complete polishing process; a polishing solution channel for channeling the flow of polishing solution to said gap; and a polishing solution supply portion for supplying the polishing solution to said polishing solution channel; wherein said polishing solution is drawn into said gap between the peripheral edge of said semiconductor wafer and said rotary body, and polishing abrasive particles in said polishing solution collide with the peripheral edge of said semiconductor wafer to conduct non-contact polishing of the peripheral edge of said semiconductor wafer.
 2. A polishing machine for a peripheral edge of a semiconductor wafer, said machine comprising: a rotary mechanism for holding a semiconductor wafer while rotating it in a prescribed direction; a rotary body which rotates relative to the semiconductor wafer while maintaining a prescribed gap from a periphery of said semiconductor wafer, having a rotary axis which is set in the same direction as the rotary axis of said semiconductor wafer, so that the rotary body and the semiconductor wafer are not in contact with each other during a complete polishing process; a polishing solution tank for immersing said rotary mechanism and said rotary body in polishing solution; and a polishing solution circulation portion for circulating the polishing solution in and out of said polishing solution tank; wherein said polishing solution is drawn into said gap between the peripheral edge of said semiconductor wafer and said rotary body, and polishing abrasive particles in said polishing solution collide with the peripheral edge of said semiconductor wafer to conduct non-contact polishing of the peripheral edge of said semiconductor wafer.
 3. The polishing machine for a peripheral edge of a semiconductor wafer according to claim 1, wherein said rotary mechanism holds a plurality of semiconductor wafers in a stacked state.
 4. The polishing machine for a peripheral edge of a semiconductor wafer according to claim 1, wherein dynamic pressure generating grooves are formed on the peripheral surface of said rotary body facing the periphery of said semiconductor wafer.
 5. The polishing machine for a peripheral edge of a semiconductor wafer according to claim 1, wherein a magnet is installed in said rotary body and a magnetic polishing solution is used as said polishing solution.
 6. The polishing machine for a peripheral edge of a semiconductor wafer according to claim 1, wherein at least the peripheral surface of said rotary body facing the periphery of said semiconductor wafer is formed of an elastic material with a hardness in the range of 7-40 Hs.
 7. The polishing machine for a peripheral edge of a semiconductor wafer according to claim 2, wherein said rotary mechanism holds a plurality of semiconductor wafers in a stacked state.
 8. The polishing machine for a peripheral edge of a semiconductor wafer according to claim 2, wherein dynamic pressure generating grooves are formed on the peripheral surface of said rotary body facing the periphery of said semiconductor wafer.
 9. The polishing machine for a peripheral edge of a semiconductor wafer according to claim 2, wherein a magnet is installed in said rotary body and a magnetic polishing solution is used as said polishing solution.
 10. The polishing machine for a peripheral edge of a semiconductor wafer according to claim 2, wherein at least the peripheral surface of said rotary body facing the periphery of said semiconductor wafer is formed of an elastic material with a hardness in the range of 7-40 Hs.
 11. The polishing machine for a peripheral edge of a semiconductor wafer according to claim 1, wherein the rotary mechanism holds a plurality of semiconductor wafers forming a cylindrical shaped stack, the rotary body is accommodated in a housing, the housing has a contact surface conforming to a circumference of the cylindrical shaped stack of the semiconductor wafers, an aperture is formed in the contact surface to expose the semiconductor wafers to the rotary body.
 12. The polishing machine for a peripheral edge of a semiconductor wafer according to claim 11, wherein the contact surface of the housing is in sealed contact with the circumference of the cylindrical shaped stack of the semiconductor wafers.
 13. The polishing machine for a peripheral edge of a semiconductor wafer according to claim 11, wherein the cylindrical shaped stack comprises disc shaped spacers to separate each of the semiconductor wafers, the diameter of the disc shaped spacers is larger than the diameter of the semiconductor wafers.
 14. The polishing machine for a peripheral edge of a semiconductor wafer according to claim 1, wherein the rotary mechanism holds a plurality of semiconductor wafers forming a cylindrical shaped stack, the rotary body has a hollow cylindrical shape for accommodating the cylindrical shaped stack of the semiconductor wafers, said prescribed gap is formed between an inner surface of the hollow cylindrical shaped rotary body and a circumference of the cylindrical shaped stack of the semiconductor wafers.
 15. The polishing machine for a peripheral edge of a semiconductor wafer according to claim 14, wherein a dynamic pressure groove is formed on the inner surface of the hollow cylindrical shaped rotary body, extending in the direction of the rotary axis of the hollow cylindrical shaped rotary body.
 16. The polishing machine for a peripheral edge of a semiconductor wafer according to claim 14, further comprising a fixed hollow cylindrical body for accommodating the hollow cylindrical shaped rotary body, a passage is formed between an outer surface of the hollow cylindrical shaped rotary body and an inner surface of the fixed hollow cylindrical body for providing the polishing solution.
 17. The polishing machine for a peripheral edge of a semiconductor wafer according to claim 14, wherein the hollow cylindrical shaped rotary body comprises n-polar and s-polar magnets alternatively arranged on its inner surface. 